A Device to Device Proximity Service (Device to Device Proximity Service, D2D ProSe for short) has become a research subject of the Rel. 12 system of a Long Term Evolution (Long Term Evolution, LTE) system in the 3rd generation partnership project (The 3rd Generation Partnership Project, 3GPP).
In the prior art, in a scenario in which a user device communicates with a base station, the user device measures quality of a channel, and then sends a measurement result to the base station. The base station sends a selected resource and modulation and coding level to the user device by using signaling. However, in a scenario in which user devices perform direct communication, because a base station does not participate in configuration and interaction processes of communication between user devices, the base station cannot learn quality of a channel between the user devices.